The maBD-1 cDNA partial sequence of Megalobrama amblycephala was cloned using RT-PCR,its distribution in different tissues and expression after pathogen invasion was investigated.The target gene was then ligated with the Plasmid pGEX-KG vector and the pGEX-KG-maBD-1 was transformed into the prokaryotic cell BL21 and expressed by chemical inducer.The polyclonal antibody of the fusion protein was acquired by the immunity to rabbit and the titer of the antibody was measured.The results showed that the length of maBD-1 open reading frame was 204bp,encoding 67 amino acids.The maBD-1 gene was widely expressed in many tissues,and the expression in the head kidney and spleen was upregulated along with the pathogen invasion.Western-bloting analysis showed that the antiserum had the ability to combine with the GST-maBD-1 protein.